تاثیر کشاورزی بر تنوع و جمعیت کرم‌های خاکی در شمال ایران

Earthworms, as ecosystem engineers, play an important role in nutrient cycling and improving soil quality, while showing high sensitivity to land-use changes. This study was conducted to investigate the effects of different agricultural land uses on the diversity and abundance of earthworms in farmlands of northern Iran, including the provinces of Golestan, Guilan, and Mazandaran, during autumn 2022. Sampling was carried out in turnip, soybean, rice, wheat, mixed vegetable–cucurbit mix, and soybean–sesame fields using the quadrat method, and species were identified based on morphological characteristics. Four species—Aporrectodea caliginosa, A. rosea, Octolasion lacteum, and Amynthas corticis—were identified, among which A. rosea was the most abundant. The highest density and species diversity were observed in the turnip field (three species with a total density of 221.33 ± 34.74 individuals m⁻²), while the lowest values were recirded in the rice paddy (one species with 20.00 ± 5.75 individuals m⁻²) and the soybean–sesame mixed field (one species with 56.00 ± 34.02 individuals m⁻²). Diversity indices also revealed significant differences among habitats, with Shannon–Wiener diversity and evenness indices in the vegetable–cucurbit field (0.46 ± 0.195 and 0.66 ± 0.280, respectively) being lower than those in other habitats (both greater than 0.60 and 0.80, respectively). The findings indicate that intensive agricultural practices such as deep plowing, the use of chemical inputs, and soil compaction play a major role in reducing earthworm diversity and density. In contrast, certain land uses such as turnip and soybean cultivation provide more favorable conditions for maintaining earthworm communities.